Process for the thermal decomposition of combustible organic liquids



Sept. 27, 1960 s ETAL 2,954,416

PROCESS FOR THE THERMAL DECOMPOSITION OF COMBUSTIBLE ORGANIC LIQUIDS Filed June 21, 1957 HyoeosaN 5 CQACKED 6A E5 XYG BUZ NEE.

CoomNG JACKET COMTANEQ Unit d States Patent PROCESS FOR THE THERMAL DECOlVIPOSITION OF COMBUSTIBLE ORGANIC LIQUIDS Alfred Schmidt and Ricardo Marin, Marl, Kreis Recklinghausen, Germany, assignors to Chemische Werke Hiils Aktiengesellschaft, Marl, Kreis Recklinghausen, Germany, a corporation of Germany Filed June 21, 1957, Ser. No. 667,097

Claims priority, application Germany Aug. 14, 1956 1 Claim. (Cl. 260-679) In our application, Serial No. 579,694, filed April 20, 1956, and now abandoned, a process is described for thermally decomposing or cracking combustible organic liquids by introducing an oxygen-containing gas into the combustible organic liquids in a quantity insuificient for complete combustion thereof, and causing the gas to burn below the surface of the liquid. In this process the oxygen oxidizes a part of the organicliquid in an inverted flame. The combustion heat generated cracks a corresponding quantity of the liquid. The cracked products formed are immediately quenched by the excess of organic liquids surrounding the flame area, so that the reaction state attained at the cracking temperature is immediately fixed.

The process is particularly suited for cracking liquid hydrocarbons into gaseous hydrocarbons. As a result of the extraordinarily favorable thermodynamic conditions existing in this arrangement it is possible to convert the liquid hydrocarbons into gaseous reaction products without noteworthy energy losses. Of theenergy content of the liquid starting hydrocarbons, 80% and more appears as combustion heat in the reaction gases, so that the losses appearing as sensible heat amount to only about 20% of the energy content of the liquid hydrocarbons consumed. The reaction products obtained in this reaction procedure, in addition to carbon monoxide, carbon dioxide and soot are hydrogen, and paraflin, olefine and acetylene hydrocarbons.

In the further development of the process for the thermal splitting of combustible organic liquids described in said application Ser. -No. 579,694 it has been found that the process can be carried out with negative pressure, i.e. under a partial vacuum, and that considerable advantages are obtained. Even with a negative pressure of down to 100 mm. Hg and below, the combustion of the oxygen in the liquid is possible and the cracking can be carried out in the manner described above. When the process is carried out under reduced pressure the ratio of acetylene present in the reaction gases increases, while the yield of soot, which is undesirable as such, is decreased. Working under a lower pressure is especially.

useful in cracking the less volatile organic liquids. Since the combustion and cracking process occurs in the gaseous phase, the conversion of the liquid into the gase ous state is favored at lower pressures and thus the course of the reaction is also influenced.

In the technical execution of the process the cracked gases collecting above the surface of the liquid are drawn 01f so strongly that the desired pressure is maintained in the space. The pressure may have any desired value. Working at 100 to 500 mm. Hg has proven to be expedient.

. 2,954,416 Patented Sept. '27,- 1960 ice.

Example 1 In the apparatus illustrated, container 1 is filled with Aramco crude oil up to the line a and cooled by water in the jacket 2. The burner 4, provided with protective bell 3, is ignited outside the container, hydrogen being supplied at 6 and oxygen at 7 in approximately equal volumes. After the ignition of the hydrogen at 5 the burner is slowly introduced so far into the oil in the container 1 that the bell lies about 5 cm. below the oil surface a. After the oil has become heated to about 40 C., the hydrogen is turned ofl and the flow of oxygen increased to about 500 liter/hour. The oxygen then burns by reaction with the vapor of the organic liquid. The oxygen continues to burn in the oil as an inverted flame. The cracked gases formed are withdrawn at 8 by means of a suitable pump, so strongly that a pressure of about 300- 400 mm. Hg is maintained in the container 1 above the surface a of the liquid. The cracked gases obtained have the following composition by volume percent, calculated as air and oxygen free gas.

The soot formation is only about 20% of the amount which is obtained in the corresponding experiments under atmospheric pressure. The amount of acetylene is appreciably greater compared to the experiments at atmospheric pressure.

Example 2 In the apparatus illustrated, the container 1 is filled with diesel oil up to the line a. The burner 4, with the protective bell 3 omitted in this experiment, is ignited outside the container, hydrogen being introduced at 6 and oxygen at 7. The quantities of hydrogen and oxygen are so adjusted that the oxygen is present in excess. After igniting the oxyhydrogen flame at the burner mouth 5 the burner is slowly dipped into the oil. After the oil has reached a temperature of about -80 C., the hydrogen is turned off completely. The quantity of oxygen is adjusted to 500 liter/hour. The cracked gases formed are withdrawn at 8 by means of an oil pump so that a pressure of about 200 mm. Hg is maintained in the container 1 above the surface of the liquid. The cracked gases obtained have the following composition in volume percent and calculated as air or oxygen free gas.

We claim:

Process for the thermal decomposition of normally liquid hydrocarbons which comprises introducing an oxygen containing gas which is free of fuel into a body of a normally liquid hydrocarbon in the liquid state in quantity insuificient for the complete combustion thereof, causing said gas to burn below the surface of said body While maintaining a subatmospheric pressure within the range from 100 to 500 mm. Hg thereon and removing the resulting gases and vapors from contact with said body at said subatmospheric pressure.

References Cited in the file of this patent UNITED STATES PATENTS Ellis June 11, 1929 Herrmann et a1 June 21, 1932 Millar Feb. 7, 1933 Wulfi j Apr. 1, 1941 

